Vehicle lamp

ABSTRACT

A vehicle lamp has a housing, a light-transmissive shield covering the housing that extends across a corner area of the vehicle, at least one lamp chamber in the housing in which a light source is positioned, and a Fresnel lens having concentrically arranged prism rings located between the light source and the light-transmissive shield adjacent to the light-transmissive shield in at least partial area. The Fresnel lens has at least one curved partial area, in order to make manufacturing as simple as possible while achieving an optimal illumination and maintaining proper light distribution. The Fresnel lens is comprised of a first curved partial area having a center of the concentrically arranged prism rings and a second partial area extending up to a side area of the lamp chamber. The partial areas have differing surface geometries and are separated from each other by vertical separating lines. The concentric prism rings continue in alignment into the other partial areas, respectively, through the separating lines.

This application is a continuation of PCT/EP 97/06337, filed Nov. 13,1997 now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to a vehicle lamp of a type having a housing, alight-transmissive shield covering the housing that extends across acorner area of a vehicle, at least one lamp chamber in the housing inwhich light source is positioned, and a Fresnel lens havingconcentrically arranged prism rings located between the light source andthe light-transmissive shield, that is placed adjacent to thelight-transmissive shield in at least one partial area.

German patent document (DE 41 17 463 C2) discloses a vehicle lamp havinga housing and a light-transmissive shield that covers the housing. Thevehicle lamp has at least one lamp chamber positioned at a corner areaof the vehicle so that light distribution is achieved along both alongitudinal axis of the vehicle and at a side of the vehicle. To createthe light distribution, a light source and a Fresnel lens that collectsthe light from the light source are placed in the lamp chamber, theFresnel lens being positioned adjacent the light-transmissive shield inat least one partial area of the light-transmissive shield and extendingessentially across the entire lamp chamber. This Fresnel lens has atleast one curved partial area.

In vehicle lamps of this design, a problem arises in illuminating theentire light-transmissive shield as evenly as possible while stillproviding a light distribution prescribed by law. The Fresnel lensesused for this purpose either have an extremely simple geometry that doesnot provide the desired light distribution, or have very expensive andcomplicated geometries that are difficult to design, the constructionand manufacture of which is highly cost-intensive.

An object of this invention is to provide a vehicle lamp that employs aFresnel lens as a light collecting device for achieving an optimized,extending-to-a-side-area-of-a-vehicle, light distribution andillumination, which at the same time can be constructed and manufacturedsimply and inexpensively.

SUMMARY

According to principles of this invention a lamp of the type set forthin the opening paragraph above has a Fresnel lens with a first curvedpartial area including a center of concentrically arranged prism ringsand a second partial area extending up to a side area of the lampchamber. The partial areas have differing surface geometries and areseparated from each other by vertical separating lines. The concentricprism rings respectively extend in alignment into the other partialareas through the separating lines.

BRIEF DESCRIPTION OF THE DRAWING

The invention is described and explained in more detail below using anembodiment shown in the drawings. The described and drawn features, inother embodiments of the invention, can be used individually or inpreferred combinations. The foregoing and other objects, features andadvantages of the invention will be apparent from the following moreparticular description of a preferred embodiment of the invention, asillustrated in the accompanying drawings in which reference charactersrefer to the same parts throughout the different views. The drawings arenot necessarily to scale, emphasis instead being placed uponillustrating principles of the invention in a clear manner.

FIG. 1 is a horizontal cross-sectional view of a vehicle lamp of thisinvention;

FIG. 2 is a more-detailed horizontal cross-sectional view of a Fresnellens of the lamp of FIG. 1; and

FIG. 3 is a front view of the Fresnel lens of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a vehicle lamp for mounting in a corner area of a motorvehicle. This vehicle lamp can be a rear-mounted light, as in theexample illustrated, or it may also be structured as a front-mountedturn-signal light, for example.

The vehicle lamp has a housing G that is covered by a light-transmissiveshield L. At least one lamp chamber K is positioned in the housing G ata corner area of the vehicle. The lamp chamber K accommodates a lightsource Q that is inserted into a lamp holder S in the housing G. Thelamp chamber K shown here has as a light collecting device a Fresnellens F that extends essentially across the entire lamp chamber K and ispositioned adjacent the light-transmissive shield L at least in onepartial area. In the embodiment illustrated here, the Fresnel lens F isdivided into three partial surfaces areas T1, T2, T3, to provide anoptimized illumination of the light-transmissive shield L in all areaswith a structure that is simplest to produce. The central partial areaT1, for example, is structured as a curved spherical surface and hasthereat a center of concentrically arranged prism rings P (not shownhere), that extend in alignment throughout all the partial areas Tl, T2,T3 of the Fresnel lens F. A light-emitting spiral-wound filament of thelight source Q is thereby positioned at a focal point of the Fresnellens F. The partial area T2 that adjoins the first partial area Tl at aside area of the vehicle lamp blends smoothly into the geometrical shapeof the first partial area T1 at an area of a vertical separating line TL12. Furthermore, the second partial area T2, at an area of its free end,matches optimally, in this area, with a surface contour of a housingwall of the housing G and/or a surface contour of the light-transmissiveshield L. For this purpose, the second partial area T2 is formed as aprism-ring P, or dispersing-element, supporting surface of freegeometry; with a tool used to create it being structured as a millingpart, for example.

For further ease of manufacture, the second partial area can also bestructured to be essentially straight, and the tool used to create itcan be a turning part.

In a variation from the embodiment illustrated here, the first partialarea T1 can extend toward a middle of the vehicle up to the housing G.In the embodiment illustrated here, however, the first partial area T1blends continuously into the third partial area T3 in an area of aseparating line TL13. In this regard, the third partial area T3 of theFresnel lens F can be structured mainly as a straight extending area,or, as in the embodiment illustrated here, it can have a conicalsurface, so that a best possible matching and a best possible transitionof the first partial area T1 into the third partial area T3 is providedin an area of the separating line TL13, since both surfaces have thesame radius in the area of the separating line TL13.

FIG. 2 clarifies the structure of the Fresnel lens F shown here by wayof example, having three partial areas T1, T2, T3 that continuouslyblend into each other at the separating lines TL12 and TL13,respectively. In addition, FIG. 2 shows a center Z of concentricallyarranged prism rings P and an associated focal point B of the Fresnellens F. FIG. 2 also shows that the Fresnel lens F spans an angle ofapproximately 90°. In other embodiments, the angle spanned by theFresnel lens F in a horizontal cross section can range between 80° and120°. In addition, FIG. 2 also shows that division of the prismcontinues smoothly and in alignment across the separating lines TL12 andTL13 into the respective adjacent contiguous surfaces. This figure alsoindicates that the prism rings P, which may be structured as totalreflection prisms and/or refraction prisms, have varying shapes indifferent areas of the Fresnel lens F that are designed respectively fordesired light distribution functions. Thus, the prism rings P around thecenter up to a free end section of the third partial area T3 areessentially structured as total reflection prisms, which deflect lightfrom the light source (not shown here) in a main direction of a beam. Inthe corner area covered by the left area of the first partial area T1,as can be seen in FIG. 2, the prism rings P achieve a light radiation oflight from the light source (not shown) in a radiation direction rangingbetween 0° and 45°. The prism rings P on the second partial area T2serve only for side illumination.

FIG. 3 shows a front view of the Fresnel lens F, illustrating the prismrings P arranged concentrically around a center Z and their continuousextension across the individual partial areas. To increase a centralillumination, refraction prisms may also be used instead of totalreflection prisms in an area indicated by the dashed lines that extendaround the center.

The Fresnel lens F is preferably manufactured as a single resinousplastic piece.

Because the center of the concentrically arranged prism rings ispositioned in the first curved partial area, the advantage is providedof the best possible utilization of the light beams radiating from thelight source, which is positioned opposite this center directly at thefocal point of the lens, for use for a light distribution area in themain radiation direction. By placing a second partial area that extendsto the side area of the lamp chamber, a simple possibility arises forbest possible side illumination light distribution.

By delimiting the individual partial areas via vertical separating lineswhile at the same time selecting various surface geometries for theindividual partial areas, a significant advantage is achieved in thateach partial area can be constructed inexpensively as a simplegeometrically formed body, and tools can be made that havesimply-structured working surface areas which are independent of eachother.

It is particularly advantageous, in this design, that the concentricprism rings continue in alignment across the separating lines into eachof the other respective partial areas, which prevents unevenillumination of the light-transmissive shield despite the combination ofindividual surfaces having differing geometries.

Structuring the first partial area as a spherical surface has provenparticularly advantageous in this process, since a tool used thereforcan be a symmetrical turning part.

The same advantages are achieved if the second and third partialsurfaces are arranged as surface elements extending essentially along astraight line. If the third partial area is structured as a conicalsurface, a tool used for its manufacture can also be made in the simpleform of a turning part.

If the second partial area is structured as a slightly curved surface offree geometry, the surface of the tool for creating the Fresnel disk forthis section can be made in a simple form as a milling part. Inselecting a surface of free geometry, a particular advantage is achievedthat the free end section of the third partial area can be adapted in anoptimal manner to a contour of the vehicle lamp in the side area, andthus to a contour of the vehicle body. In current vehicle bodies, thisarea is often curved in all directions.

By dividing the first partial area into spherical surfaces havingvarying radii, an advantage is achieved that the Fresnel lens can beadapted to a desired light distribution and a contour of thelight-transmissive shield in an area of greatest curvature of theFresnel lens.

By adapting the surface contours of the individual partial areas inareas of the separating lines to the respective adjacent partial areas,a significant advantage is achieved that the partial areas of theFresnel lens blend smoothly into each other without sudden shifts,whereby a negative influence on illumination is prevented andmanufacture is made more simple. In this context, it has provenparticularly advantageous to manufacture the entire Fresnel lens withall the partial areas as a single piece, in one work process.

Particularly uniform illumination is achieved if the concentric prismrings continue in alignment in all partial areas.

The invention claimed is:
 1. A vehicle lamp comprising:a housing at acorner side of a vehicle, a light-transmissive shield covering thehousing, at least one lamp chamber in the housing in which a lightsource is positioned, and a Fresnel lens having concentrically arrangedprism rings located between the light source and the light-transmissiveshield that is placed adjacent to the light-transmissive shield at leastin one partial area, wherein the Fresnel lens is comprised of a curvedfirst partial area having a center of the concentrically arranged prismrings and a second partial area extending up to a side area of the lampchamber, and wherein the first and second partial areas have differingsurface geometries, wherein the first and second partial areas areseparated from each other by vertical separating line the concentricprism rings continue in alignment between the partial areas,respectively, through the separating line, and said concentricallyarranged prism rings are comprised of total reflection prism rings andrefraction prism rings, wherein said total reflection prism rings andsaid refraction prism rings are positioned around said center of saidcurved first partial area.
 2. A vehicle lamp as in claim 1, wherein thefirst partial area is a spherical surface.
 3. A vehicle lamp as in claim2, wherein the second partial area runs essentially in a straight line.4. A vehicle lamp as in claim 1, wherein the second partial area is aslightly curved surface of free geometry.
 5. A vehicle lamp as in claim1, wherein a third partial area is contiguous with the first partialarea for extending toward a middle of the vehicle which is separatedfrom the first partial area by a vertical separating line.
 6. A vehiclelamp as in claim 5, wherein the third partial area extends substantiallyin a straight line.
 7. A vehicle lamp as in claim 5, wherein the thirdpartial area is a conical surface.
 8. A vehicle lamp as in claim 1,wherein the first partial area is constructed of spherical surfaceshaving different radii.
 9. A vehicle lamp as in claim 5, wherein thepartial areas match the surface contours of the respective adjacentpartial surfaces at their separating lines.
 10. A vehicle lamp as inclaim 1, wherein the Fresnel lens is structured as one piece includingall of the partial areas.
 11. A vehicle lamp as in claim 1, wherein theconcentric prism rings continue in alignment throughout all of thepartial areas.
 12. A vehicle lamp as in claim 1, wherein the Fresnellens spans an angle ranging between 80° and 120° in a horizontalsection.
 13. A vehicle lamp as in claim 12, wherein the Fresnel lensspans an angle of approximately 90°.